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Discussion Starter #1
1999 dodge 2500, 230k miles. 5 speed manual. This is similar to a post I made a year and a half ago when my 4wd vac shift motor was going out. Turns out I had two problems.

I have a long, steep gravel driveway. Whenever I go up the hill, I throw it in 4wd to save wear on tires and the road. In 4wd only, there is a loud 'clunk' that you can feel through the entire truck. It is momentary, and occurs usually once in the 300' to the house. It does it going straight or it might do it when I'm taking a slight turn. No pattern to it. The 4wd light does not go off, and there is proper pressure at the vac motor.

It does not do this going level or downhill, or turning on either of those. I can drive in 4wd 6 miles to work and it won't happen-- when roads are icy of course, and it is a straight and level drive.

I rebuilt both front and rear driveshafts-- not the problem. FYI-- the Spicer u-joints were original to the truck and still had miles in them. The center bearing was toast.

The axle u joints, bearings and ball joints seem fine. I do all my own work, but I might take it to Schwab and see if they can see anything.

The transfer case has never been serviced-- maybe a stretched chain? It's a 241 DLD, built in 10/98.

My next step is to replace fluids: tranny, tc and diff's.

Anyway, any thoughts would be appreciated.
 

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Odd question, but are all 4 tires the same size?
 

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Only once? Never backing up and braking or in 2x4? In the middle of the hill or at the beginning or end of the run? If the TC has never been apart it is likely fine. Is is shifting up or down at the trani when it happens? If it is after moving I would suspect suspension.
Are you sure the CAD has already locked in or is it when it locks in?
 

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Discussion Starter #4
It only does it once, rarely twice in 300'. Never backing up or braking, in 4x4 or 2x4. Random where it does it up the hill-- beginning to end. I'm usually in 2nd gear, 4hi, unless i'm pulling a trailer, then 1st gear, 4hi.

Cad is locked for sure-- won't make it up my driveway in 2wd this time of year.

Here is what I'm hoping-- I just had to adjust the linkage on my JDeere-- it kept popping out of gear. So I just adjusted the linkage a smidge on the Dodge-- I ran the driveway 3 times and it went fine. Fingers crossed this is the issue. The linkage shows no signs of having slipped, but it is only one nut and this problem has been going on for awhile.

Thanks for the reply-- I never even thought about this as a possible solution. Time will tell.
 

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if you are talking about the linkage on the transfer case, adjusting it will make no difference unless the shift lever was hitting something. The adjustment only changes the shift lever angle position in the cab. Shifting and position is controlled inside the TC by the rotating slot plate and indent on the CAD vacuum switch. The lever just moves those parts, they hold it in whatever position/gear you put it in.
You did say the TC has never been apart right? There is some retainers and locks inside the TC that can allow it to jump out of gear for a second if broken or installed incorrectly. Usually this only happens from mechanic error going back together. Do you have a DLD or DHD TC? It is possible but very very rare fo a chain to stretch and slip
Check the bolts on top and bottom of the trani motor mount for loose or missing. Check rubber too. they can cause it to rock and clunk under torque.
 

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Discussion Starter #6
I agree with you-- don't see how adjusting the linkage would work, but what have I got to lose, right?

DLD 241-- never been apart, and it has never been abused. Has fluid-- about a 3/4" low from the bottom of the fill plug-- that's going to get changed this weekend. Was just underneath there rebuilding the front drive shaft-- everything looks fine and dandy.

When I get that 'thunk' the 4wd light stays on.

This sure has me stumped. I think I'll take it to a shop and pay for a diagnosis, if they can find one. That's always dicey-- the shop I used on rear occasions is under new ownership-- they might just want to change my Framistat and headlight oil... lol.
 

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Look close a tthat rear trani mount, bolts and rubber. I had one that was loose and when on throttle on a hill it would rock up and drip back down and clunk.
Make sure exhaust pipe is not hitting something, it has happened.
No grinding, just clunk?
Most clunks come from two things, bad control arm bushings and bad track bar busing/ends. But those would usually be under different situations.
Check both pinion bearings for lateral or end play.
What is your location?
 

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Discussion Starter #9
Trannie mount seems fine-- I was just in there, removing the tranny support cross member (what a ). It was and is fine and solid. Exhaust pipe has no movement. No grinding-- just one big clunk that feels like an axle just broke in half. The truck shudders from it.

I put the truck up on jackstands and put it 4wd... and let her run for awhile. It never did it. Everything inside the vac shift motor housing looks fine.

It is so random-- the only consistent thing is 4wd high on a hill. Hmmm... never thought about trying 4wd low...

I'll look at the control arm bushings. This forum thread sounds alot like what I'm experiencing; https://dodgeforum.com/forum/2nd-gen-ram-tech/347340-intermittent-4wd-issue-clunking-while-driving-binding-noise.html

Thanks. I'm no mechanic-- I just play one after watching youtube.

Pullman, WA.
 

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I know you want to be in 4x4 but try this:
Remove the front drive line.
Put it in 4x4while running.
Shutoff
try turning the front yoke on the TC and see how much slack is in chain. The sole purpose of the chain is to turn the front drivel line.
Now while it is out let you rear tires down to 30-35lbs for traction and try you hill a couple of times that would unload the chain.
Has it come back yet since adjustment?

Why did you have crossmember out if not working on TC? PS is is not that hard if done right. What color is the front vacuum line attachment on the TC tubes on the transfer case?
 

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Discussion Starter #11
Crossmember was off to rebuild the front driveshaft u joints. Actually, got it mostly off, following all the advice the internet offered, except using a bottlejack and 4x4 to press the frame apart. I thought it would just drop out... silly me.

Color-- I'll have to check later.

I've ran my hill 4x since the adjustment-- no thunk. If this fixes it, I have no idea how.

When I was manually turning the hub at the transfer case when the driveline was off, I wasn't detecting any play, but not sure if that can be detected by hand. It seems tight though, at the yoke, when muscling down the driveshaft bolts while it was in 4wd.

thx.
 

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If it was worn enough to cause a problem you would feel the change in resistance slack. But worn chains are not usually a problem.
Now this ain't going to make you feel any better this time bu will save a lot of trouble next time.
Skid plate removal may be necessary but cross member is not required for drive line removal. Though it is easier, it is not even necessary for transfer case or overdrive removal.
Spreading the frame is absolutely the wrong way to remove it.
The correct way is to:
Raise the back of trani to near floor board.
Remove hold down brackets on brake lines and hold fuel lines near crossmember.
Push/tap the crossmember UP about 2 inches. It its in a taper in the frame. Pushing it UP release it and it slides back easily if you have not bent it badly pounding on it previously.
Drive line bolts can be easily removed by doing the front first so you can rotate and putting a bar through the yoke to hold it where you want it and doing the transfer case end bolts on the top side with a socket and wobbly extension 3/8.

You can do almost everything on these trucks yourself, but be sure and hit us up here first for tips and instructions. It will save you a lot of time, pain, heartache and money.


Anyway let me know if it holds or comes back.
 

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Discussion Starter #13
Thanks for the cross member tip: dammit, that was a PIA!

While I have you here, my fuel pumps were changed about 14 years/100,000 miles ago. Fuel pressure is a constant 10-12 psi. Leave 'em be? Switch 1 or both out? Keep a spare lift pump in the tool box? Thx.
 

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I ate up a 241DLD in my 12V. I was in 2wd though when I found it. I was towing my fifth wheel and randomly, when under load I would hear a bang and it would wouldn't happen for ahwile. Eventually it happened more frequently and I figured out it was something in the t-case. Once I tore the t-case down I found that the shift forks in a 241DLD have little plastic bushings that sit on them. These plastic bushings prevent metal on metal wear between the shift collar and shift fork. What happened was they worn down and fell out. That allowed the shift collar to move about an 1/8" under load. Once that collar moved as much as it could it started to wear the shift fork down which was now metal on metal. As that wore it allowed the shift collar to move even more. The popping was the shift collar actually jumping teeth. Once it jumped enough and rounded the leading edge of the teeth off it didn't have enough engagement and stripped the gear and collar.

You said you adjusted it and it seems better but you saw no indication that the linkage had moved previously. I would drain the fluid and look for any metal shavings very carefully. Or even plastic pieces, as the shift fork bushings were laying in the bottom of the case when I disassembled it.
 

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That is a reasonable possibility. I would check as he indicated. maybe add putting a magnet in the drain hole for chunks. When shift forks are damaged they do not move everything into gear and lock position allowing it to jump out as he indicated.

As far a lift pump goes i think that is fine for stack and near stock trucks. I have had the in tank pump for about 7 years and 200k now(have 700k total mi). If you are holding around 10+ on a hill or cruising you are fine. Do you have permanent gauge.

This and several other thing I believe in " If it ain't broke . don't fix it."
Mor issues come about with these trucks by screwing with or mis-repairing something than break on their own. On the other hand, especially suspension and steering, when ever you find a part/system with wear and play in it fix it right away.
I am not saying spend money on all these talked about mods and "special" parts, jusdt but good parts and keep the systems up to snuff without play in things.

I hear people say "it is OK, just a little play in it" WRONG, NO play is OK on most things. A little here and a little there adds up to wondering or death wobble etc. Just keep everything tight and well adjusted. Extra Caster does help as does 0 to 1/8 in toe in, no more.
 

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Discussion Starter #16
@silver. thanks. That's my plan this weekend-- jack up the front of the truck 8", drain the oil and stick a camera snake in there to see what's at the bottom of the case.
 

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That will be interesting. Pretty tight in there, don't know how much to get a look at. Try both drain and fill hole. Shift fork and collar will be to the upper right of the fill hole and the low range to the left of it I think.
There is a round magnet in the bottom front of the case where the oil pickup. but big chunks can settle in the bottom near the drain. Plugs are not magnetic.
Look for the fork issues he described(plastic tips missing, bent or broken forks, and for the snap ring holding the shift collar on
If it comes back I expect you will have pull it. We will get to that if needed later.
 

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Discussion Starter #18
Ok, jacked up the front of the truck--- drained the fluid from the tc. Fluid is ugly-- brown and dirty. So filled with Dex iii and took it for a spin. No clunking-- seems to shift into 4wd easier.

You were right that it was a pretty tight fit for the snake. I couldn't tell if there were pieces of plastic at the bottom of the case. What I do see though fills me with dread-- cracks at the back of the case. Take it apart or just leave it be?

thx...
 

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I don't think that is cracks unless they leak. What looks like cracks on the TC is usually just lines and slag from casting. Pretty common on the 241 but that is a bit more than usual. OH, I see that is on the inside which is even more common.
 

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Discussion Starter #20
Dammit, got two knocks coming up my driveway yesterday. First one wasn't as heavy as the second, but you can feel it under your feet. Only thing left to check is front diff-- I'll do that today. Maybe Schwab can give me a diagnosis this morning.
 
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